Utilizing thermal isostasy to estimate sub-lithospheric heat flow and anomalous crustal radioactivity

Helium in the Australian liquefied natural gas economy

“…The relative higher R/Ra in the Browse Basin (Fig. 7) may indicate a local area of higher sub-lithospheric heat flow (Hasterok and Gard 2016). Gases from the Canning Basin have the second highest average helium content with a dominant crustal helium source (Figs 6 and 7) and are in accord with a restricted hot spot in radiogenic heat flow in this region (Hasterok and Gard 2016).…”

“…7) may indicate a local area of higher sub-lithospheric heat flow (Hasterok and Gard 2016). Gases from the Canning Basin have the second highest average helium content with a dominant crustal helium source (Figs 6 and 7) and are in accord with a restricted hot spot in radiogenic heat flow in this region (Hasterok and Gard 2016). A high sub-lithospheric heat flow is also predicted along the easternÀsouth-eastern edge of Australia in response to much younger Cenozoic tectonism (Cull and Conley 1983;Hasterok and Gard 2016) and concur with natural gases with the highest mantle 3 He inputs (R/Ra > 1; Bass, Gunnedah and Otway basins; Fig.…”

“…For example, surface heat flow is a combination of mantle and crustal inputs, and the general dipartite division of high heat flow between radiogenic heat flow in eastern Australia and sub-lithospheric (mantle) heat flow in western Australia (Hasterok and Gard 2016) …”

Heat Flow in Southern Australia and Connections With East Antarctica

“…Importantly, variations in heat flow observed at the surface (i.e., those most relevant to ice sheet stability) are a result of contributions from both mantle heat flow and/or radiogenic heat produced within the crust. This means that the crustal contribution to surface heat flow is critically important to constrain via in situ measurements, particularly given that in stable cratonic regions such as Antarctica and southern Australia, mantle heat flow variations are likely to be small (<10 mW/m 2 ; Hasterok & Gard, ). As a result, it is unlikely that heat flow trends reflect fluctuations in mantle heat flow; rather, numerous studies from southern Australia confirm that the predominant cause is heterogeneous crustal heat production (McLaren et al, ; McLaren et al, ; Neumann et al, ; Sandiford et al, ).…”

“…Plate tectonic reconstructions ( Figure 1) indicate that beneath the thick cover of ice, East Antarctica contains rocks with affiliations to Australia, Africa, and India (Aitken, Betts et al, 2016;Daczko et al, 2018;Ferraccioli et al, 2011;Flowerdew et al, 2013;Mulder et al, 2019), all of which were adjoined prior to the breakup of Gondwana during the Jurassic (Boger, 2011). Geochemical and geophysical studies indicate that both the observed heat flow and crustal heat production across these continents is highly variable (Carson et al, 2014;Cull, 1982;Hasterok & Gard, 2016;Jones, 1987;Nyblade et al, 1990;Roy & Rao, 2000). Heat flow in tectonically stable regions is largely controlled by crustal characteristics and the resulting crustal component of heat flow (Förster & Förster, 2000;Mareschal & Jaupart, 2013).…”